I did a lot of research and this is the best bang for your buck. I got my first one and fried it out and contacted the company and sent it in. They sent me a new one really quick no questions asked You can do heating and cooling with this one. The digital part rocks!

The digital comes with a electronic sensor. The manual one comes with a liquid filled bulb with a hollow tube to determine temperature. If the line gets kinked (as mine did) you have a useless piece of garbage. I ended up getting the digital.

you would need to wire the unit, unless you get a prewired unit. The controller plugs into your wall outlet, then the freezer plugs into the controller. Place the sensor inside the freezer and set your temp. The controller will then control the cycling of your freezer.